The invention relates to an apparatus for needling a non-woven material with a support receiving at least one needleboard, which support is drivable in a reciprocating fashion both in the needle-penetration direction as well as the direction of passage of the non-woven material and on which are coupled the connecting rods of two oppositely driven eccentric drives for the drive in the needle-penetration direction and on which there acts at least one additional eccentric drive.
In order to reduce the draft of a non-woven material drawn continuously by a needling apparatus on the one hand and to increase the advance of the non-woven material on the other hand it is known (DE 196 15 697 A1) to provide an additional eccentric drive for a needleboard movement in the direction of passage of the non-woven material in addition to the needleboard drive reciprocating in the needle-penetration direction, so that due to the movement component of the needles in the direction of passage of the non-woven material the tensile load of the non-woven material as occurs during the needle penetration is reduced or the advance of the non-woven material is increased accordingly. In order to set the oscillating amplitude of the needleboard in the direction of passage of the non-woven material, it has already been proposed in this connection (EP 0 892 102 A2) to equip the additonal needleboard drive with two parallel eccentric shafts whose connecting rods are mutually connected by a coupler linked to a support for the needleboard. By making a respective choice of the mutual angular position of the two eccentric shafts it is possible to set the needleboard advance in the direction of passage of the non-woven material. This simple possibility for adjustment is gained with the disadvantage that the support which is coupled with the connecting rods of the two eccentric drives for the needleboard drive in the needle-penetration direction performs a reciprocating swivelling movement which produces a respective swivelling movement of the needlings in the non-woven material during the needle penetration.
For two mutually opposite needleboards which are used alternatingly it is known (DE 2 264 257 A) to arrange said needleboards in a common frame which is driven reciprocatingly in the needle-penetration direction via an eccentric drive, while the additional movement component in the direction of passage of the non-woven material is ensured by two oppositely driven eccentric drives which each act on the frame via a connecting rod and simultaneously assume its guidance in the needle-penetration direction in form of a parallelogram of links. This known design does not allow any setting of the oscillating amplitude of the frame in the direction of passage of the non-woven material.
The invention is based on the object of providing an apparatus for needling a non-woven material of the kind mentioned above in such a way that advantageous conditions are provided on the one hand for a construction of a needleboard drive of low complexity both in the needle-penetration direction as well as in the direction of passage of the non-woven material and on the other hand for a simple setting of the needleboard advance in the direction of passage of the non-woven material without having to swivel the needleboard.
This object is achieved by the invention in such a way that the connecting rods of the two oppositely driven eccentric drives extend in opposite directions with respect to the needle-penetration direction, that the additional eccentric drive revolves synchronously with one of the two other eccentric drives, that the connecting rod of the additional eccentric drive which is also coupled with the support forms a parallelogram of links for guiding the support with the connecting rod of the synchronously revolving eccentric drive, and that the oppositely drivable eccentric drives are provided with a phase shift or are adjustable with respect to the mutual angular position.
Since the connecting rods of the two oppositely drivable eccentric drives for the needleboard drive in the needle-penetration direction are not provided, as is otherwise usual, with a central position extending in the needle-penetration direction but extend inclined in opposite directions with respect to the needle-penetration direction, the support for the needleboard can be driven along an inherently closed trajectory by a phase shift between said two eccentric drives, which allows an advantageous adjustment of the needle movement to the advancement of the non-woven material when the support is guided parallel with respect to itself. For this purpose the connecting rod of the additional eccentric drive forms a parallelogram of links with the connecting rod of the synchronously revolving eccentric drive of the two other eccentric drives, which ensures the parallel guidance of the support and thus a swivel-free needle penetration into the non-woven material. Since already a comparatively small mutual offset of the angular position of the two eccentric drives revolving in opposite directions will produce a curved path for the support with a respective component in the direction of passage of the non-woven material, the horizontal component of the needleboard drive can be adjusted in a sensitive way to the respective conditions via the phase shift of the oppositely driven eccentric drives, namely with a relatively low amount of constructional effort.
Although an additional eccentric drive is sufficient for the parallel guidance of the support, particularly simple constructional conditions are obtained with respect to the balancing of masses when two additional eccentric drives are provided which revolve synchronously with one each of the two other eccentric drives and form a parallelogram of links each with the same.
The eccentric drives forming a parallelogram of links for guiding the support can be arranged differently depending on the spatial conditions. It is possible for example to arrange the eccentric drives forming a parallelogram of links for guiding the support behind one another in the needle-penetration direction, which allows a compact overall length. In order to reduce the overall height the eccentric drives forming a parallelogram of links for guiding the support can be arranged adjacent to one another in the direction of passage of the non-woven material, which naturally entails a longer overall length. Such different arrangements of the eccentric drives forming a parallelogram of links for guiding the support have no influence on the curve path of the support. As a result of the parallel guidance of the support this also applies in the case that the connecting rods of the two eccentric drives which are drivable in opposite directions are not linked at a mutual distance to the support, but via a common coupling shaft. The shape of the curve path of the support depends on the one hand on the phase shift between the oppositely drivable eccentric drives and on the other hand on their eccentricity, the length of the connecting rods and the mean inclination of the connecting rods with respect to the needle-penetration direction, so that the trajectories of the supports can be designed via these influencing variables for certain needle-penetration conditions. If for example the connecting rods are provided on the side of the eccentric drive which is averted from the needleboard, the course of the trajectories offers considerably better needle-penetration conditions for many applications than in an arrangement in which the connecting rods are provided on the side of the eccentric drives which faces the needleboard.